Pathomechanics of Glenohumeral joint

pathomechanics of shoulder joint,
clinical significance of shoulder muscle, axiohumeral muscles, scapulohumeral muscles,

1. PATHOMECHANICS OF GLENOHUMERAL JOINT PRESENTED BY : - SYED ADIL [MUSCULOSKELETAL PHYSIOTHERAPY] DEPARTMENT

2. SCAPULOHUMERAL MUSCLES DELTOID - [ANT, MID, POST] SUPRASPINATUS INFRASPINATUS SUBSCAPULARIS TERES MINOR TERES MAJOR

3. DELTOID

4. ANTERIOR DELTOID ACTION SHOULDER FLEXION HORIZONTAL ADDUCTION

5. WEAKNESS of the anterior deltoid muscle is likely to produce weakness in shoulder flexion. However, weakness may also result in diminished strength of shoulder, shoulder abduction, and horizontal adduction. TIGHTNESS of the anterior deltoid can contribute to diminished shoulder extension and lateral rotation ROM

6. POSTERIOR DELTOID ACTIONS SHOULDER EXTENSION HORIZONTAL ABDUCTION

7. EFFECT OF WEAKNESS OF THE Posterior D eltoid Include decreased shoulder extension strength. EFFECT OF TIGHTNESS of the posterior deltoid include restricted shoulder flexion and horizonal adduction ROM.

8. MIDDLE DELTOID – [ACTION : ABDUCTION] Loss of the middle deltoid weakens, but does not eliminate, active abduction of the shoulder It is unlikely that tightness of the middle deltoid muscle actually can restrict shoulder adduction ROM. However, the position of shoulder adduction applies tension to the middle deltoid and may cause pain or additional disruption to the tendon of the deltoid or the bursa lying deep to it.

9. SUPRASPINATUS – ACTIONS ABDUCTION DYNAMIC STABILIZATION

10. The supraspinatus muscle is the most superior muscle of the rotator cuff group. It lies deep to the subacromial (subdeltoid) bursa, the coracoacromial ligament, and the deltoid muscle and acromion process. The supraspinatus muscle participate specifically in stabilizing the glenohumeral joint in the inferior direction (dynamic stabilizer)

11. The supraspinatus helps stabilize the glenohumeral joint by exerting a horizontal pull to hold the humeral head against the glenoid process.

12. INFERIOR SUBLUXATION OF GLENOHUMERAL JOINT

13. The proposed function of the supraspinatus in preventing the inferior subluxation of the glenohumeral joint is facilitated by the upward tilt of the glenoid fossa Weakness of the trapezius may contribute to inferior subluxations of the joint. (example upper extremity weakness following stroke) Thus the inferior subluxation of the glenohumeral joint may be the result of the combined effects of weakness of the supraspinatus and trapezius muscles

14. Thus, t reatment approaches should include exercises to restore an upward tilt of the glenoid fossa while facilitating the activity of the rotator cuff muscles (supraspinatus)

15. WEAKNESS OF THE SUPRASPINATUS MUSCLE can result from :- D enervation secondary to an entrapment of the suprascapular nerve M echanical disruption of the muscle’s tendon or its insertion into the glenohumeral joint capsule I nhibition of muscle contraction caused by pain secondary to such disorders as tendinitis

16. WEAKNESS of the supraspinatus is manifested by a significant decrease in the strength and endurance of shoulder abduction TIGHTNESS of the supraspinatus tendon is unlikely, but it can be present following surgical repair of a rotator cuff tear.

17. INFRASPINATUS ACTION LATERAL ROTATION HORIZONTAL ABDUCTION STABILIZATION

18. Isolated WEAKNESS of the infraspinatus is unusual but has been reported. It is manifested clinically by a significant reduction in the strength of lateral rotation of the shoulder. Tightness of the infraspinatus contributes to decreased ROM of shoulder medial rotation and may also contribute to decreased horizontal adduction ROM.

19. TERES MINOR ACTION LATERAL ROTATION ADDUCTION STABILIZATION

20. Weakness of the teres minor can contribute to a decrease in the strength of shoulder lateral rotation. However, since the physiological cross-sectional area of the teres minor is so much smaller than that of the other lateral rotators, the decrease in lateral rotation strength is unlikely to be significant.

21. SUBSCAPULARIS ACTION INTERNAL ROTATION ADDUCTION STABILIZATION

22. WEAKNESS of the subscapularis results in a significant decreasein strength of shoulder medial rotation. Weakness of the subscapularis may also contribute to anterior instability of the glenohumeral joint.

23. CLINNICAL RELAVANCE SUBSCAPULARIS WEAKNESS: Decreased activation of the subscapularis is reported in some individuals who can sublux their glenohumeral joints spontaneously using lateral rotation. Muscle re-education to facilitate the subscapularis and other medial rotators is an important component of the rehabilitation program to increase stability.

24. TIGHTNESS of the subscapularis causes decreased lateral rotation ROM at the shoulder. Tightness of the subscapularis muscle sometimes is induced deliberately to improve joint stability surgically in individuals with chronic anterior dislocations of the glenohumeral joints

25. TERES MAJOR ACTION ADDUCTION INTERNAL ROTATION

26. The teres major exhibits EMG activity with the shoulder held in static positions of flexion or abduction a nd it is is also able to pull on the scapula when the humerus is held fixed . Thus, the teres major assist in stabilizing the scapulothoracic joint rather than to move or hold the glenohumeral joint.

27. The tightness can also influence the resting position and mobility of the scapulothoracic joint. It can pull the scapula into a position of abduction and upward rotation, contributing to another variant of the rounded-shoulders posture. T IGHTNESS of the teres major can be expected to result in restricted ROM in shoulder lateral rotation, flexion, and abduction.

28. -: SUMMARY :- SCAPULOHUMERAL MUSCLES RESTRICTED ROM DYNAMIC STABILITY

29. AXIOHUMERAL MUSCLES PECTORALIS MAJOR LATISSIMUS DORSI

30. PECTORALIS MAJOR The pectoralis major has two distinct bellies, a smaller clavicular portion and a much larger sternal portion

31. ACTIONS :- SHOULDER FLEXION (CLAVICULAR FIBRES) SHOULDER EXTENSION FROM FLEXED POSITION (STERNAL FIBRES) MEDIAL ROTATION SHOULDER DEPRESSION RESPIRATION

32. WEAKNESS of the whole pectoralis major may result in decreased strength in medial rotation, adduction, horizontal adduction of the shoulder, and shoulder depression. TIGHTNESS of the pectoralis major is likely to restrict shoulder abduction and flexion ROM as well as lateral rotation ROM of the shoulder.

33. LATISSIMUS DORSI ACTIONS EXTENSION ADDUCTION MEDIAL ROTATION SHOULDER DEPRESSION The latissimus dorsi is a broad flat muscle with an extensive attachment on the spine and pelvis, suggesting that this muscle is capable of generating large forces

34. CLINICAL RELEVANCE LATISSIMUS DORSI PEDICLE FOR RECONSTRUCTIVE SURGERY: Because of its size and vascular supply from multiple arteries, the latissimus dorsi is a frequent source of grafting material for reconstructive surgery, including wound closures and breast reconstruction. Such surgery can significantly impair the strength of the shoulder from which the latissimus dorsi is taken

35. The latissimus dorsi is an important muscle in swimming and is very strong and perhaps overdeveloped in competitive swimmers. TIGHTNESS of the latissimus dorsi limits shoulder ROM in flexion, lateral rotation, and perhaps abduction. Consequently, tightness of the latissimus dorsi also may contribute to flexion of the upper thoracic spine i.e . a tight latissimus dorsi may contribute to increased thoracic kyphosis.

36. SHOULDER DEPRESSION The force of shoulder depression is particularly important when the upper extremity is used in weight-bearing activities. For example, as a person uses a cane, the arm is bearing weight. The reaction force of the cane tends to elevate the shoulder. Active contraction of the shoulder depressors stabilizes the shoulder, preventing elevation.

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